These days, numerous detection and analysis methods for determining physiological parameters in bodily fluid samples or other biological samples are performed in a large number and in an automated manner in automatic analysis instruments, also so-called in vitro diagnostic systems.
Current analysis instruments are able to perform a multiplicity of detection reactions and analyses using one sample. In order to be able to perform a multiplicity of examinations in an automated manner, various devices for the spatial transfer of measurement cells, reaction containers, and reagent containers are necessary, such as, e.g., transfer arms with a gripper function, transport belts, or rotatable transport wheels, as are devices for transferring liquids, such as, e.g., pipetting devices. The instruments comprise a control unit which, by means of appropriate software, is able to plan and work through the work steps for the desired analyses in a largely independent manner.
Many of the analysis methods used in such analysis instruments operating in an automated manner are based on optical processes. These methods render possible the qualitative and quantitative detection of analytes, i.e., the substances in samples to be detected or determined. Clinically relevant parameters, such as, e.g., the concentration or activity of an analyte, are often determined by virtue of part of the sample being mixed with one or more test reagents in a reaction vessel, which can also be the measurement cell, as a result of which, for example, a biochemical reaction or a specific binding reaction is initiated, which brings about a measurable change of an optical or other physical property of the test run.
Samples can be fed to analysis instruments in sample collection tubes, which are sealed by a seal that can be pierced by a needle. Alternatively, the sample collection tubes can also be open or opened prior to being fed to the analysis instrument. In the analysis instrument, parts of the sample or the whole sample can be taken from the sample collection tube by means of a needle and transferred into other containers. Here, an exact alignment of the needle is necessary as the needle must hit the often relatively small opening or the relatively small seal of the sample collection tube and, at the same time, should not touch the edge of the sample collection tube in order, for example, to avoid the needle bending. Furthermore, it is necessary for the pipetting needle to hit relatively small openings of cuvettes, washing stations, or retaining devices precisely. Sample tubes and reaction vessels can be situated in receptacle positions on a linearly movable or rotatable assembly.
In particular, modern analysis instruments can be equipped with apparatus for determining the position for pipetting needles. Using this, it is possible to adjust pipetting needles and, in part, also monitor these for bending, as may occur through use or collisions. Furthermore, the correct assembly after replacing a pipetting needle can be verified, for example, by determining the position of the pipetting needle tip. If need be, a deviation in the position of the pipetting needle tip from the intended position can also be achieved by an appropriate displacement of the pipetting needle. A pipetting needle is usually assembled on a transfer arm.
Interacting assemblies, such as, e.g., a linearly movable assembly or a rotatable assembly with receptacle positions for sample tubes and, e.g., a linearly movable transfer arm with a pipetting needle, a gripper, or a gauge must be precisely adjusted relative to one another. Here, the linearly movable assembly and the linearly movable transfer arm or the rotatable assembly and the linearly movable transfer arm can be arranged at different angles to one another. By way of example, in an automatic analysis system, a rotatable assembly can also interact with a plurality of linearly movable transfer arms, which are located at different angles in relation to the rotatable assembly. For adjustment purposes, use is usually made of a plurality of reference abutment points with known position coordinates. The interacting assemblies are usually adjusted by hand by a skilled service technician, which often means significant outlay and is connected with high costs.